﻿// http://www.zimms.com
// Copyright (c) 2002-2007
// by James Zimmerman
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in the
// Software without restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
// Software, and to permit persons to whom the Software is furnished to do so, subject
// to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies
// or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

using System;

/// <summary>
/// Simple validator harness for performing checks on any instance of a type.
/// </summary>
/// <typeparam name="T">The type to validate.</typeparam>
public class Validator<T> : IRule<T>
{
    private readonly IEnumerable<IRule<T>> rules;

    /// <summary>
    /// Initializes a new instance of the <see cref="Validator{T}"/> type with the supplied <see cref="IRule{T}">rules</see>.
    /// </summary>
    /// <param name="rules">A parameter array of <see cref="IRule{T}">rules</see> for the validator to operate with.</param>
    public Validator(params IRule<T>[] rules) : this((IEnumerable<IRule<T>>)rules) { }

    /// <summary>
    /// Initializes a new instance of the <see cref="Validator{T}"/> type with the supplied <see cref="IRule{T}">rules</see>.
    /// </summary>
    /// <param name="rules">The arrays of <see cref="IRule{T}">rules</see> for the validator to operate with.</param>
    public Validator(IEnumerable<IRule<T>> rules)
    {
        this.rules = rules ?? new IRule<T>[] { };
    }

    /// <summary>
    /// Validates the supplied object optionally returning a modified instance.
    /// </summary>
    /// <param name="item">The object to validate.</param>
    /// <returns>The optionally modified instance.</returns>
    /// <exception cref="ValidationException">Thrown when an validation exception occurs.</exception>
    public T Evaluate(T item)
    {
        try
        {
            foreach (IRule<T> rule in this.rules)
            {
                if (rule == null) continue;

                item = rule.Evaluate(item);
            }

            return item;
        }
        catch (EvaluationException ex)
        {
            throw new ValidationException(ex.Message, ex);
        }
    }
}


/// <summary>
/// Exception for representing validation issues.
/// </summary>
[Serializable()]
public class ValidationException : EvaluationException
{
    /// <summary>
    /// Initializes a new instance of the <see cref="ValidationException"/> class.
    /// </summary>
    public ValidationException() { }

    /// <summary>
    /// Initializes a new instance of the <see cref="ValidationException"/> class with a specified error message and a reference to the inner exception that is the cause of this exception.
    /// </summary>
    /// <param name="message">The message that describes the error.</param>
    /// <param name="innerException">The exception that is the cause of the current exception, or <see langkeyword="null">null</see> if no inner exception is specified.</param>
    public ValidationException(String message, Exception innerException) : base(message, innerException) { }

    /// <summary>
    /// Initializes a new instance of the <see cref="ValidationException"/> class with a specified error message
    /// </summary>
    /// <param name="message">The message that describes the error.</param>
    public ValidationException(String message) : base(message) { }
}
